Autodiscovery with tkined tkined

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6.5.1.2 Autodiscovery with tkined

For a small network, manually drawing a diagram doesnt take very long. But for large networks, this can be a very tedious process. Fortunately, tkined provides tools for the automatic discovery of nodes and the automatic layout of maps. You begin with Tools IP-Discover. What this does is add the IP Discover menu to the menu bar. The first two items on this menu are Discover IP Network and Discover Route. These tools will attempt to discover either the devices on a network or the routers along a path to a remote machine. When one of these is selected, a pop-up box queries you for the network number or remote device of interest. Unfortunately, tkined seems to support only class-based discovery, so you must specify a class B or a class C address although you can specify a portion of a class B network by giving a class C style subnet address, e.g., 172.16.1.0. It also tends to be somewhat unpredictable or quirky when trying to discover multiple networks. If you are using subnets on a class B address, what seems to work best is to run separate discovery sessions and then cut and paste the results together. This is a little bit of a nuisance, but it is not too bad. This was what was actually done to create Figure 6-1 . Figure 6-2 shows the output generated in discovering a route across the network and one of the subnets for the network shown in Figure 6-1 . This window is automatically created by tkined and shows its progress during the discovery process. Note that it is sending out a flood of ICMP ECHO_REQUEST packets in addition to the traceroute-style discovery packets, the ICMP network mask queries, and the SNMP queries shown here. Figure 6-2. Route and network discovery with tkined If you do end up piecing together a network map, other previously discussed tools, such as traceroute, can be very helpful. You might also want to look at your routing tables with netstat. There are a couple of problems in using tkined. Foremost is the problem of getting everything installed correctly. You will need to install Tcl, then Tk, and then scotty. scotty can be very particular about which version of Tcl and Tk are installed. You will also need to make sure everything is in the default location or that the environmental variables are correctly set. Fortunately, packages are available for 125 some systems, such as Linux, that take care of most of these details automatically. Also, tkined will not warn you if you exit without saving any changes you have made.

6.6 Politics and Security